Giant hydroelectric dams being built or planned in remote areas of Brazil, Ethiopia, Malaysia, Peru and Guyana will devastate tribal communities by forcing people off their land or destroying hunting and fishing grounds, according to a report by Survival International today.

The first global assessment of the impact of the dams on tribes suggests more than 300,000 indigenous people could be pushed towards economic ruin and, in the case of some isolated Brazilian groups, to extinction.

The dams are intended to provide much-needed,low-carbon electricity for burgeoning cities, but the report says tribal people living in their vicinity will gain little or nothing. Most of the power generated will be taken by large industries, it concludes.

At least 200,000 people from eight tribes are threatened and a further 200,000 people will be adversely affected by the Gibe III dam on the Omo river in Ethiopia. Ten thousand people in Sarawak,…